Typically, police cars, fire engines, ambulances, and other emergency vehicles employ a light bar. These light bars provide a visual warning signal of the approach of the emergency vehicle. The light bar is positioned on the roof of the vehicle so that oncoming traffic can see the emergency vehicle.
In most visual warning devices, it is the generally accepted practice to sweep one or more beams of light through a plane of rotation. A flashing or constantly varying signal, emanating from the source, is thus presented to an observer position some distance therefrom. In most cases, the beam is rotated within a flat plane to alert the observer while, in others, the beam may be oscillated above and below the plane of rotation to produce what is called a "wig-wag" signal.
Typically, two techniques are employed to generate a moving light signal and, thus, create a flashing effect. The most common approach is to simply mount a number of light sources upon a rotatable platform and rotate the entire structure about a common axis of rotation. Alternatively, warning devices employing a stationary light source have been devised in which moving reflectors are passed through a stationary light beam to create a flashing effect. In each of these cases, the light signal requires a relatively large and cumbersome housing.
In most light bars employed in emergency vehicles, the light bars are positioned on the roof of the vehicle and extend above the roof of the vehicle for a considerable distance. The positioning of the light bar can have detrimental effects with respect to the maximum speed of the vehicle and the fuel economy of the vehicle. These light-bars cause a great deal of wind resistance as the vehicle moves through traffic. In many circumstances, these light bars are made of a plastic material that is subjected to damage and deterioration. Often, it is very difficult to attach these light bars to the vehicle. These light bars also can be extremely expensive.
Under certain circumstances, it is desirable for the emergency vehicle to appear as inconspicuous as possible. Typically, police cars employed in "unmarked" duty or in undercover duty will not use a conspicuous light bar. Many times, these vehicles have the light bar installed in the interior of the vehicle or detachably positioned on the roof of the vehicle. When the light bar placed within the vehicle, it is often difficult for observers to see the flashing lights from all directions. Those flashing signals that are removably positioned on the roof of the vehicle will be cumbersome to install and often become dislodged during the fast movement of the vehicle.
In the past, various U.S. patents have been granted which describe various types of light bars. U.S. Pat. No. 3,633,161, issued on Jan. 4, 1972, to Charles Price describes a rotating beacon which is in the shape of a pyramid having upwardly and inwardly extending corners defining a plurality of sides. The corners provide a discernible reduction in light so as to give a pattern of intermittent flashing of light from the side panels of the pyramid upon rotation. The bottom of the pyramid is enclosed with a reflective member and a gear wheel which allows the pyramid to be rotated by an electrical motor.
U.S. Pat. No. 4,104,615, issued on Aug. 1, 1978, to E. T. Hunter teaches a flashing light signal that includes a rotatably mounted signal generator formed of a light transmitting material and a non-rotatable source of light adapted to direct light into the generator upon its axis of rotation. A pyramid-shaped prism is associated with the generator having its apex positioned along the axis of rotation. The prism surfaces intercept the light directed into the generator, split the light into one or more beams, and direct the beams toward the exit face that is substantially perpendicular to the axis of rotation.
U.S. Pat. No. 5,000,535 describes a fiberoptic light bar employed in a display fixture. In this patent, a fiberoptic bundle is extended into the interior of the housing. A light source is connected to the end of the bundle so as to provide light to the interior of the housing. Each of the ends of the fiberoptics face outwardly of the housing.
U.S. Pat. No. 5,122,933 describes a perimeter message and clearance lighting for a cargo vehicle container body. A pair of elongated fiberoptic cables are individually encased in a correspondingly elongated enclosure so as to illuminate the interior of the enclosure and to pass light through an outward translucent face of the enclosure so as to present a graphic message. The fiberoptic cables are constructed to propagate light flux longitudinally and radially.
U.S. Pat. No. 5,165,774, issued on Nov. 24, 1992, to G. R. Windross describes a fiberoptic wide-angle illuminating device. This device includes a yoke having a C-shaped head for receiving and supporting output ends of the optical fibers in a splayed-out fashion in a row. A single wide-angle optical lens is aligned in a predetermined relationship with a single aperture for receiving light emitted from the optical fibers through the aperture and for projecting the light in a desired beam pattern.
U.S. Pat. No. 5,193,893, issued on Mar. 16, 1993, to M. A. Mitko provides a vehicle hood deflector for attachment to the hood of a vehicle so as to project above it. The interior of the enclosure is illuminated so as to make a visible sign on the front of the enclosure. A fiberoptic cable has input terminals illuminated by the vehicle headlights and output terminals extending into the enclosure so as to illuminate the signs by the headlights.
U.S. Pat. No. 5,276,594, issued on Jan. 4, 1994, to Burkett et al. provides an add-on vehicle safety light monitor. A light pipe is provided which has an input end and an output end. The light pipe is configured to be supported upon the vehicle body at a position in which the input end is approximate to the to-be-monitored light source and the output end is viewable by the vehicle driver or operator.
It is an object of the present invention to provide a light bar that has a relatively short profile.
It is another object of the present invention to provide a light bar that improves the aerodynamics of the vehicle to which it is attached.
It is another object of the present invention to provide a light bar that reduces the number of moving parts and electronics.
It is a further object of the present invention to provide a light bar that is attractive, produces the necessary luminance, and is easy to install.
It is still a further object of the present invention to provide a light bar that is relatively inexpensive and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.